const mapHelper = {
	/**
	 *  判断经纬度是否超出中国境内
	 */
	isLocationOutOfChina:function(latitude, longitude) {
	  if (longitude < 72.004 || longitude > 137.8347 || latitude < 0.8293 || latitude > 55.8271)
	    return true;
	  return false;
	},
	
	
	/**
	 *  将WGS-84(国际标准)转为GCJ-02(火星坐标):
	 */
	transformFromWGSToGCJ:function(latitude, longitude) {
	  var lat = "";
	  var lon = "";
	  var ee = 0.00669342162296594323;
	  var a = 6378245.0;
	  var pi = 3.14159265358979324;
	
	  if (isLocationOutOfChina(latitude, longitude)) {
	    lat = latitude;
	    lon = longitude;
	  }
	  else {
	    var adjustLat = transformLatWithXY(longitude - 105.0, latitude - 35.0);
	    var adjustLon = transformLonWithXY(longitude - 105.0, latitude - 35.0);
	    var radLat = latitude / 180.0 * pi;
	    var magic = Math.sin(radLat);
	    magic = 1 - ee * magic * magic;
	    var sqrtMagic = Math.sqrt(magic);
	    adjustLat = (adjustLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);
	    adjustLon = (adjustLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * pi);
	    latitude = latitude + adjustLat;
	    longitude = longitude + adjustLon;
	  }
	  return { latitude: latitude, longitude: longitude };
	
	},
	
	/**
	 *  将GCJ-02(火星坐标)转为百度坐标:
	 */
	transformFromGCJToBaidu: function(latitude, longitude) {  
	  var pi = 3.14159265358979324 * 3000.0 / 180.0;
	
	  var z = Math.sqrt(longitude * longitude + latitude * latitude) + 0.00002 * Math.sin(latitude * pi);
	  var theta = Math.atan2(latitude, longitude) + 0.000003 * Math.cos(longitude * pi);
	  var a_latitude = (z * Math.sin(theta) + 0.006);
	  var a_longitude = (z * Math.cos(theta) + 0.0065);
	
	  return { latitude: a_latitude, longitude: a_longitude };
	},
	/**
	 *  将百度坐标转为GCJ-02(火星坐标):
	 */
	transformFromBaiduToGCJ: function(latitude, longitude) {
	  var xPi = 3.14159265358979323846264338327950288 * 3000.0 / 180.0;
	
	  var x = longitude - 0.0065;
	  var y = latitude - 0.006;
	  var z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * xPi);
	  var theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * xPi);
	  var a_latitude = z * Math.sin(theta);
	  var a_longitude = z * Math.cos(theta);
	
	  return { latitude: a_latitude, longitude: a_longitude };
	},
	
	/**
	 *  将GCJ-02(火星坐标)转为WGS-84:
	 */
	transformFromGCJToWGS: function(latitude, longitude) {
	  var threshold = 0.00001;
	
	  // The boundary
	  var minLat = latitude - 0.5;
	  var maxLat = latitude + 0.5;
	  var minLng = longitude - 0.5;
	  var maxLng = longitude + 0.5;
	
	  var delta = 1;
	  var maxIteration = 30;
	
	  while (true) {
	    var leftBottom = transformFromWGSToGCJ(minLat, minLng);
	    var rightBottom = transformFromWGSToGCJ(minLat, maxLng);
	    var leftUp = transformFromWGSToGCJ(maxLat, minLng);
	    var midPoint = transformFromWGSToGCJ((minLat + maxLat) / 2, (minLng + maxLng) / 2);
	    delta = Math.abs(midPoint.latitude - latitude) + Math.abs(midPoint.longitude - longitude);
	
	    if (maxIteration-- <= 0 || delta <= threshold) {
	      return { latitude: (minLat + maxLat) / 2, longitude: (minLng + maxLng) / 2 };
	    }
	
	    if (isContains({ latitude: latitude, longitude: longitude }, leftBottom, midPoint)) {
	      maxLat = (minLat + maxLat) / 2;
	      maxLng = (minLng + maxLng) / 2;
	    }
	    else if (isContains({ latitude: latitude, longitude: longitude }, rightBottom, midPoint)) {
	      maxLat = (minLat + maxLat) / 2;
	      minLng = (minLng + maxLng) / 2;
	    }
	    else if (isContains({ latitude: latitude, longitude: longitude }, leftUp, midPoint)) {
	      minLat = (minLat + maxLat) / 2;
	      maxLng = (minLng + maxLng) / 2;
	    }
	    else {
	      minLat = (minLat + maxLat) / 2;
	      minLng = (minLng + maxLng) / 2;
	    }
	  }
	},
	
	isContains: function(point, p1, p2) {
	  return (point.latitude >= Math.min(p1.latitude, p2.latitude) && point.latitude <= Math.max(p1.latitude, p2.latitude)) && (point.longitude >= Math.min(p1.longitude, p2.longitude) && point.longitude <= Math.max(p1.longitude, p2.longitude));
	},
	
	transformLatWithXY:function(x, y) {
	  var pi = 3.14159265358979324;
	  var lat = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));
	  lat += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
	  lat += (20.0 * Math.sin(y * pi) + 40.0 * Math.sin(y / 3.0 * pi)) * 2.0 / 3.0;
	  lat += (160.0 * Math.sin(y / 12.0 * pi) + 320 * Math.sin(y * pi / 30.0)) * 2.0 / 3.0;
	  return lat;
	},
	transformLonWithXY: function(x, y) {
	  var pi = 3.14159265358979324;
	  var lon = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
	  lon += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
	  lon += (20.0 * Math.sin(x * pi) + 40.0 * Math.sin(x / 3.0 * pi)) * 2.0 / 3.0;
	  lon += (150.0 * Math.sin(x / 12.0 * pi) + 300.0 * Math.sin(x / 30.0 * pi)) * 2.0 / 3.0;
	  return lon;
	}
}

export default mapHelper